APS Cam870 "Snap cap"

thingiverse

I'm testing a dummy shell for dry firing purposes. To get the receiver to cycle properly, you'll need to file the 45-degree angle on the flange flat. I'm not entirely sure if this approach works as intended; it could just be wishful thinking. You may need to double or triple the spring tension, but that's probably better than nothing. The spring in question is a 6.5mm OD x 17.5mm length model. Please post your findings, and I'll feel warm and fuzzy inside!